Conventionally, on vehicles such as automobiles, a wiper apparatus for wiping off adhesive substances such as rain, snow, and sprays from preceding vehicles from a windshield to secure visibility of a driver is provided. Among the wiper apparatuses provided to the vehicles, an opposite type wiper apparatus, in which a pair of motors rotating in forward and backward directions is opposingly allocated on a left side and a right side of the vehicle in order to comply to constriction of location spaces of the wiper apparatuses inside an engine compartment et al., is known. This opposite type wiper apparatus is, by rotating each motor in the forward and the backward directions, configured to perform a reciprocating wiping action by a pair of wiper blades which are allocated to overlap in a center portion of the windshield. Therefore, the opposite type wiper apparatus, compared to a popular wiper apparatus (tandem type wiper apparatus) which performs the reciprocating wiping action of the pair of wiper blades by a single motor via a linking mechanism, is made feasible that movable portions including the linking mechanism is made smaller, and is able to comply to the constriction of the allocation spaces.
For the opposite type wiper apparatus, for example, an art described in Patent Document 1 (Japanese Patent Application Laid-Open Publication No. 11-301409) is known. The opposite type wiper apparatus described in Patent Document 1 performs a synchronous operation of a driver-seat side (DR-side) motor and a passenger-seat side (AS-side) motor by a controller, so that a DR-side wiper blade and an AS-side wiper blade are allowed to perform reciprocating wiping actions over the windshield without interfering each other. And, the synchronous operation of each motor is performed based on pulse signals outputted according to rotation of each motor, and the controller compares true position data (measured value) of each wiper blade with reference position data (target value) of each wiper blade previously memorized in a nonvolatile memory (ROM), and controls each wiper motor rotatably so that the measured value nears the target value.